Mobile asset location tracking systems have been available since the 1980s. These systems typically place a locator sensor, such as a Global Positioning System (GPS) receiver, and some sort of wireless data communicator system, such as a cellular telephone, to periodically transmit its location to a central dispatch or controller. Knowing the location of trailers has proven to be extremely valuable to trailer operations. Initially, this technology was primarily utilized for exception management, but it has since proven to also be valuable for improving the efficiency of trailer utilization.
One key piece of information used in optimizing trailer utilization is to know when and where a trailer was loaded, and when and where the trailer was unloaded. Until recently, trailer operations relied on the accuracy of reports from drivers for this information, but historically, this method of reporting is often inaccurate.
Object detection techniques utilizing ultrasonic transducers has also been available for years, but the application of this invention for cargo detection in a trailer had not been exploited until just recently. Ultrasonic detectors address a key issue in trailer cargo detection in that the sensor can be mounted in one location, and the detection signal originates and returns to that same location. Consequently, the installation and cost is manageable.